Process for preparing block copolymer of monoolefin

ABSTRACT

A process for preparing a block copolymer of an α-olefin and a vinyl compound is here disclosed which comprises the steps of polymerizing an olefin selected from ethylene and the α-olefin having 3 or more carbon atoms by the use of a divalent or a trivalent rare earth metal complex, and then polymerizing a vinyl compound, a vinylidene compound or a lactone. According to the process of the present invention, a polar group can be introduced into a polyolefin, whereby the characteristics of the polymer can be effectively improved.

This application is a continuation of application Ser. No. 08/267,747,filed Jul. 5, 1994, now U.S. Pat. No. 5,563,219.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a process for preparing a blockcopolymer of a monoolefin and a vinyl compound, a vinylidene compound ora lactone. More specifically, it relates to a process for preparing theabove-mentioned block copolymer in accordance with a livingpolymerization method by the use of a specific catalyst.

(b) Description of the Prior Art

In general, a polyolefin is poor in chemical reactivity and adhesiveproperties to another resin, is hardly dyed with a dye or a pigment, andhas a large gas permeability.

In order to solve these problems, it has been carried out tograft-polymerize a monomer having a polar group to a polyolefin.

Alternatively, as another method, it has already been reported by thesame inventors as in this application that by the use of a lanthanoidecatalyst, methyl methacrylate or a lactone can be furtherblock-copolymerized to a polymerization-active terminal at whichethylene is polymerized (Japanese Patent Application Laid-open No.255116/1991 & which corresponds to U.S. Pat. Nos. 5,132,369 and5,218,064). This publication discloses that according to the abovemethod, the block copolymer of ethylene and the vinyl compound or thelactone can be prepared, but a block copolymer of an α-olefin having 3or more carbon atoms and a vinyl compound or a lactone is not disclosedanywhere. The polymerization of ethylene is relatively simple, and acopolymer with ethylene can also easily be prepared. For example, theethylene copolymer can easily be prepared even in accordance with aradical polymerization method. As random copolymers, copolymers ofethylene-acrylate, ethylene-vinyl acetate and the like have beenindustrially produced in large quantities. However, if the preparationof a copolymer by the use of an α-olefin of 3 or more carbon atoms suchas propylene is intended in accordance with a similar procedure, themolecular weight of the obtained copolymer is low, and for this reason,it is very difficult to obtain the useful copolymer. Thus, any effectivemethod has not been known. In the above-mentioned patent, the blockcopolymer of ethylene has been disclosed, but copolymer of an α-olefinhaving 3 or more carbon atoms is neither disclosed nor suggestedanywhere.

The method disclosed in the above-identified Patent cannot polymerize anα-olefin having 3 or more carbon atoms, such as propylene, and thereforethe method is not capable of obtaining a block copolymer of an α-olefinhaving 3 or more carbon atoms and a vinyl compound or a lactone.

SUMMARY OF THE INVENTION

The present inventors have intensively investigated into a process forpreparing a block copolymer of a monoolefin, particularly an α-olefinhaving 3 or more carbon atoms and a vinyl compound, a vinylidenecompound or a lactone which can solve the above-mentioned problems. Inconsequence, the present invention has been completed.

That is to say, a first aspect of the present invention is directed to aprocess for preparing a block copolymer of a monoolefin and a vinylcompound which comprises the steps of polymerizing an α-olefin having 3or more carbon atoms by the use of a divalent or a trivalent rare earthmetal complex, and then polymerizing a vinyl compound, a vinylidenecompound or a lactone.

A second aspect of the present invention is directed to a process forpreparing a block copolymer of a monoolefin which comprises the steps ofpolymerizing ethylene by the use of a divalent rare earth metal complex,and then polymerizing a vinyl compound, a vinylidene compound or alactone.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A catalyst for use in the present invention is a divalent or a trivalentrare earth metal complex, and the complex is represented by thefollowing formula (1) or (2) and it can be singly used. ##STR1## whereinCp is a cyclopentadienyl residue;

R¹ is a substituent on the cyclopentadienyl group and it is an alkylgroup or a silicon-containing hydrocarbon residue having 1 to 20 carbonatoms;

X is a divalent hydrocarbon residue or a silicon-containing hydrocarbonresidue having 1 to 20 carbon atoms;

j is an integer of 1 to 5;

Ln is a trivalent rare earth metal selected from the group consisting ofY, Sc, La, Ce, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Sm, Yb and Lu;

R² is an alkyl group or a silicon-containing hydrocarbon residue having1 to 12 carbon atoms;

a Donor is a compound selected from the group consisting of a ketone, anester, an ether and an amine having 1 to 12 carbon atoms; and

n is 0 or 1. ##STR2## wherein Cp is a substituted cyclopentadienylresidue;

R¹ is a substituent on the cyclopentadienyl group and it is an alkylgroup or a silicon-containing hydrocarbon residue having 1 to 20 carbonatoms;

X is a divalent hydrocarbon residue or a silicon-containing hydrocarbonresidue having 1 to 20 carbon atoms;

j is an integer of 1 to 5;

Ln is a divalent rare earth metal selected from the group consisting ofSm, Yb and Eu;

a Donor is a compound selected from the group consisting of a ketone, anester, an ether and an amine having 1 to 12 carbon atoms; and

m is an integer of from 0 to 2.

In the process of the present invention, among the above-mentionedcatalysts, a divalent or a trivalent compound represented by the formula(3) or (4) can be preferably used. ##STR3## wherein Cp is a substitutedcyclopentadienyl residue;

Me₃ Si is a trimethylsilyl group and tBu is a tertiary butyl group, andthe cyclopentadienyl residue is substituted by these groups at the2-position and the 4-position thereof, respectively;

R⁴ is a methyl group or a bistrimethylsilylmethyl group;

R³ is an alkyl group having 1 to 20 carbon atoms; Ln is a trivalent rareearth metal selected from the group consisting of Y, Sc, La, Ce, Pr, Nd,Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Sm, Yb and Lu;

a Donor is a compound selected from the group consisting of a ketone, anester, an ether and an amine having 1 to 12 carbon atoms; and

n is 0 or 1. ##STR4## wherein Cp is a substituted cyclopentadienylresidue; Me₃ Si is a trimethylsilyl group and tBu is a tertiary butylgroup, and the cyclopentadienyl residue is substituted by these groupsat the 2-position and the 4-position thereof, respectively;

R² is an alkyl group having 1 to 20 carbon atoms;

Ln is a divalent rare earth metal selected from the group consisting ofSm, Yb and Eu;

a Donor is a compound selected from the group consisting of a ketone, anester, an ether and an amine having 1 to 12 carbon atoms; and m is aninteger of from 0 to 2.

In the process of the present invention, a monoolefin is firstpolymerized, and the polymerization of a vinyl compound, a vinylidenecompound or a lactone is then carried out to obtain a block copolymer.

Examples of an α-olefin which can be used in the present inventioninclude α-olefins having 3 to 20 carbon atoms. The α-olefins can becopolymerized with each other, or the α-olefin can be copolymerized withethylene in an amount of 50 mol % or less of the α-olefin. Furthermore,after the polymerization of the α-olefin, the resultant polymer can bethen polymerized with another α-olefin and/or ethylene. Typical examplesof the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene,1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene,1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene,1-octadecene, 1-nonadecene, 1-eicosene and 4-methylpentene.

When the divalent rare earth metal complex of the formula (2),particularly the compound of the formula (4) is used as the catalyst,the polymerization can be efficiently carried out even by substitutingethylene for the α-olefin having 3 to 20 carbon atoms. In this case, theactivity of the catalyst is higher as compared with a case where thetrivalent rare earth metal complex is used, and what is better, apolyethylene having a relatively high molecular weight can beconveniently produced, so that a high-molecular weight block copolymercan be characteristically obtained.

In the present invention, the usable vinyl compound or vinylidenecompound is a compound having an electron-attractive substituent Zrepresented by the formula (5)

    H.sub.2 C═CR.sup.5 Z                                   (5)

wherein

R⁵ is hydrogen or an alkyl group having 1 to 12 carbon atoms; and

Z is an electron-attractive residue.

Examples of the electron-attractive residue include esters residue, ahalogen residue, a cyano residue and a phenyl group substituted by thecyano residue. These vinyl compound or vinylidene compound may be usedsingly or in combination. Particularly preferable examples of thecompound represented by the formula (5) include esters of acrylic acidand esters of methacrylic acid, and typical examples thereof includemethyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate,phenyl acrylate, methyl methacrylate, ethyl methacrylate, propylmethacrylate, n-butyl methacrylate and phenyl methacrylate.

Examples of the lactone include cyclic esters having 3 to 10 carbonatoms, and typical preferable examples thereof include propyllactone,valerolactone and caprolactone.

In the present invention, the polymerization can be achieved by a usualsolvent polymerization method, a mass polymerization method or a gaseousphase polymerization method. In view of the fact that the polymerizationis carried out in a living state, it is preferable that a polymerizationtemperature is relatively low. The polymerization temperature is usuallyin the range of -100° to 100° C., preferably -20° to 40° C. Noparticular restriction is put on a polymerization pressure, and it is inthe range of from atmospheric pressure to 50 kgf/cm² (kilogram-force persquare centimeter). The above polymerization conditions can be appliedto the various block copolymerizations, and they can be optionallychanged in the above ranges.

According to the practice of the process of the present invention, ablock copolymer of an α-olefin can be obtained, and so the presentinvention is very valuable from an industrial viewpoint. Furthermore,when a divalent complex is used, the block copolymer in which apolyethylene moiety has a large molecular weight can be obtained, whichmeans that the present invention also has an industrially large value.

Now, the present invention will be described in more detail withreference to examples, but the scope of the present invention should notbe limited to these examples.

EXAMPLE 1

0.3 mol of t-butyl bromide was added dropwise at 0° C. to atetrahydrofuran (THF) solution containing 0.3 mol of cyclopentadienylsodium salt. After reaction at the same temperature for 2 hours, thereaction was further continued at 20° C. for 18 hours. Next, thereaction product was washed with aqueous hydrochloric acid, neutralized,dried, and then distilled to obtain 11 g of a colorless liquidt-butylcyclopentadiene. This t-butylcyclopentadiene was then reactedwith an equimolar amount of n-butyl lithium to obtain a lithium salt (90mmols). Afterward, 5.8 g of a THF solution of dichlorodimethylsilane wasadded dropwise at -78° C. to a THF solution of this lithium salt,followed by reaction at 20° C. for 24 hours. THF was distilled off fromthe reaction solution, and the resultant residue was extracted withheptane and a dissolved portion was then concentrated to obtain 12.6 gof a yellow liquid. Next, 84 mmols of n-butyl lithium was added dropwiseat -78° C. to the THF solution of this yellow liquid, and reaction wasthen carried out at 0° C. for 6 hours. The THF solution of 9.1 g oftrimethylsilane chloride was added thereto at -78° C., and reaction wasthen carried out at 20° C. for 24 hours. THF was distilled off from thereaction solution, and the resultant residue was extracted with heptane,and then filtered, and a dissolved portion was then concentrated toobtain 16.6 g of a light yellow liquid. Next, this liquid was reactedwith 4.5 g of potassium hydride in decalin under a nitrogen atmosphereat 160° C. for 2 hours. From the reaction product, a yellow precipitatewas separated, dried, dissolved in THF, and then filtered to removeexcess potassium hydride which was the insoluble material, and theresultant filtrate was concentrated to obtain a yellow solid. This solidwas washed with heptane, and then dried to obtain 14.4 g of a yellowsolid. According to an NMR analysis, it was confirmed that the thusobtained solid was a potassium salt ofdimethylsilylenebis(2-trimethylsilyl-4-t-butylcyclopentadiene).

Afterward, 1.5 g (3 mmols) of this potassium salt was dissolved in 30 mlof THF, and an equimolar amount of a THF solution of samarium diiodidewas added dropwise thereto under a nitrogen atmosphere at 20° C. Afterreaction for 24 hours, the solution was concentrated to about 15 ml,followed by filtration. Next, the resultant filtrate was added to hexaneto precipitate a violet solid, and this solid was then collected byfiltration to obtain 1.1 g ofdimethylsilylenebis(2-trimethylsilyl-4-t-butylcyclopentadiene)samarium(II)THFcomplex (Me₂ Si(2-Me₃ Si-4-tBu-C₅ H₂)₂ Sm(THF)₂). This product couldscarcely be identified by NMR, and so it was changed to a trivalentcomplex by the Am. Recknagel et al's method Angew. Chem., 103, p. 720(1991)! and measurement was then made by NMR, whereby it was confirmedthat the product was the desired compound.

In a 100 ml flask were placed 60 ml of toluene and 1 mmol of a divalentsamarium catalyst represented by the formula Me₂ Si(2-Me₃ Si-4-tBu-C₅H₂)₂ Sm(THF)₂ at 25° C. under an argon gas stream, and 2.5 g of1-pentene was then added thereto with stirring. After polymerization wascarried out for 6 hours at 25° C., a part of the solution was taken outand 40 mmol of methyl methacrylate was further added, and thepolymerization was further continued for 2 hours. After the reaction, asmall amount of methanol was added thereto for deactivation. Theresultant polymer was washed with methanol, and then dried. Before andafter the addition of methyl methacrylate, molecular weights of thepolymers were measured by a gel permeation chromatography. As a result,it was apparent that the molecular weight of the polymer before theaddition of methyl methacrylate was 25,000, but that of the finallyobtained polymer was 900,000, whereby it could be confirmed that thepolymerization successively proceeded. Moreover, before and after theaddition of methyl methacrylate, ratios of weight-average molecularweights to number-average molecular weights were 1.3 and 1.6,respectively, which meant that these molecular weights were very closeto each other. According to an infrared absorption spectrum, it wasapparent that the polymer before the addition of methyl methacrylate waspoly(1-pentene), and it could be confirmed that polymethyl methacrylatewas present in the finally obtained polymer and so a block copolymer wasobtained. The yield of the polymer was 7.42 g per g of the samariumcatalyst.

EXAMPLE 2

The same procedure as in Example 1 was carried out except that methylmethacrylate was replaced with caprolactone, and as a result, a blockcopolymer having a number-average molecular weight of 180,000 wasobtained. Furthermore, a ratio of a weight-average molecular weight tothe number-average molecular weight was 1.5, which meant that thesemolecular weights were very close to each other. According to aninfrared absorption spectrum, the presence of polycaprolactone wasconfirmed, and so it could be confirmed that a block copolymer wasobtained. The yield of the polymer was 4.2 g per g of a samariumcatalyst.

EXAMPLE 3

As a catalyst, Me₂ Si(2-Me₃ Si-4-tBu-C₅ H₂)₂ YCH(SiMe₃)₂ in which acentral metal was yttrium was synthesized in a manner described inExample 1, and polymerization was then done by the same procedure as inExample 1 except that this catalyst was used. Consequently, a polymerbefore the addition of methyl methacrylate had a number-averagemolecular weight of 160,000, but a finally obtained polymer had that of400,000, whereby it could be confirmed that the polymerizationsuccessively proceeded. Furthermore, before and after the addition ofmethyl methacrylate, ratios of weight-average molecular weights tonumber-average molecular weights were 1.4 and 1.7, respectively, whichmeant that these molecular weights were very close to each other.According to an infrared absorption spectrum, it was apparent that thepolymer before the addition of methyl methacrylate was poly(1-pentene),and it could be confirmed that polymethyl methacrylate was present inthe finally obtained polymer and so a block copolymer was obtained. Theyield of the polymer was 1.45 g per g of the yttrium catalyst.

EXAMPLE 4

The same procedure as in Example 3 was carried out except that methylmethacrylate was replaced with caprolactone, and as a result, a blockcopolymer having a number-average molecular weight of 210,000 wasobtained. Furthermore, a ratio of a weight-average molecular weight tothe number-average molecular weight was 1.7, which meant that thesemolecular weights were very close to each other. According to aninfrared absorption spectrum, the presence of polycaprolactone wasconfirmed, and so it could be confirmed that a block copolymer wasobtained. The yield of the polymer was 1.32 g per g of a yttriumcatalyst.

EXAMPLE 5

In a 100 ml flask were placed 20 ml of toluene and 0.02 mmol of adivalent samarium catalyst represented by the formula Me₂ Si(2-Me₃Si-4-tBu-C₅ H₂)₂ Sm(THF)₂ at 25° C. under an argon gas stream, andethylene was then added thereto with stirring. After polymerization wascarried out for 2 hours at 25° C., the flask was purged with argon.Afterward, a part of the resultant precipitate was taken out and 10 mmolof methyl methacrylate was further added, and the polymerization wasadditionally continued for 2 hours. After the reaction, a small amountof methanol was added thereto for deactivation. The resultant polymerwas washed with methanol, and then dried. Before and after the additionof methyl methacrylate, molecular weights of the polymers were measuredby a gel permeation chromatography. As a result, it was apparent that anumber-average molecular weight of the polymer before the addition ofmethyl methacrylate was 180,000, but that of the finally obtainedpolymer was 300,000, whereby it could be confirmed that thepolymerization successively proceeded. Furthermore, before and after theaddition of methyl methacrylate, ratios of weight-average molecularweights to number-average molecular weights were 1.6 and 1.5,respectively, which meant that these molecular weights were very closeto each other. According to an infrared absorption spectrum, it wasapparent that the polymer before the addition of methyl methacrylate waspolyethylene, and it could be confirmed that polymethyl methacrylate waspresent in the finally obtained polymer and so a block copolymer wasobtained. The yield of the polymer was 8.25 g per g of the samariumcatalyst.

EXAMPLE 6

The same procedure as in Example 5 was carried out except that methylmethacrylate was replaced with caprolactone, and as a result, a blockcopolymer having a number-average molecular weight of 200,000 wasobtained. Furthermore, a ratio of a weight-average molecular weight tothe number-average molecular weight was 1.6. According to an infraredabsorption spectrum, it could be confirmed that a polycaprolactone wascopolymerized. The yield of the polymer was 6.13 g per g of a samariumcatalyst.

What is claimed is:
 1. A process for preparing a block copolymer of anα-olefin which comprises polymerizing an α-olefin having 3 or morecarbon atoms by the use of a trivalent rare earth metal complex, andthen polymerizing a vinyl compound or a lactone to said α-olefin polymerwherein the trivalent rare earth metal complex is a compound representedby the following formula (3) ##STR5## wherein Cp is a substitutedcyclopentadienyl residue;Me³ Si is a trimethylsilyl group and tBu is atertiary butyl group, and the cyclopentadienyl residue is substituted bythese groups at the 2-position and the 4-position thereof, respectively;R⁴ is a methyl group or a bistrimethylsilylmethyl group; R³ is an alkylgroup having 1 to 20 carbon atoms; Ln is a trivalent rare earth mealselected from the group consisting of Y, Sc, La, Ce, Pt, Nd, Pm, Eu, Gd,Tb, Dy, Ho, Er, Tm, Sin, Yb and Lu; Donor is a compound selected fromthe group consisting of a ketone, an ester, an ether and amine having 1to 12 carbon atoms; and n is 0 or
 1. 2. The process according to claim 1wherein the α-olefin having 3 or more carbon atoms is an α-olefin having3 to 20 carbon atoms.
 3. The process according to claim 2, wherein thevinyl compound is at least one compound represented by the formula

    H.sub.2 C═CR.sup.5 Z

wherein R⁵ is hydrogen or an alkyl group having 1 to 12 carbon atoms;and Z is an electron-attractive residue.
 4. The process according toclaim 1, wherein the vinyl compound is an ester of an unsaturatedcarboxylic acid.
 5. The process according to claim 1, wherein the vinylcompound is a vinylidene compound.
 6. The process according to claim 1wherein the vinyl compound is at least one compound represented by theformula H₂ C═CR⁵ Z wherein R⁵ is hydrogen or an alkyl group having 1 to12 carbon atoms; and Z is an electron-attractive residue.
 7. The processaccording to claim 1 wherein the vinyl compound is an ester of anunsaturated carboxylic acid.
 8. The process according to claim 1,wherein a lactone is polymerized to said α-olefin polymer and thelactone is a cyclic ester having 3 to 10 carbon atoms.
 9. The processaccording to claim 8, wherein the lactone is propyllactone,valerolactone and caprolactone.